1. Field of the Invention
The present invention relates to a hose for gasohol fuel for use in piping for transporting alcohol-blended gasoline (gasohol) and the like.
2. Description of the Related Art
In recent years, regulations on fuel gas transpiration surrounding automobiles are becoming severer, and it is required to drastically reduce transpiration of fuels from fuel-system hoses. In response, various low-permeability fuel hoses for automobiles are being studied. As one of such fuel-system hoses, a fuel filler hose for transporting volatile hydrocarbons has been proposed (for example, PCT Japanese Translation Patent Publication No. 2005-522639). This fuel filler hose includes (a) a relatively thin inner layer of an FKM fluoropolymer in an elastomer form, (b) one or more further relatively thin intermediate layers which are thermoplastic molded products prepared by extrusion-molding a THV fluoropolymer into a tubular shape over the inner FKM layer, the intermediate THV layer being integral with the FKM inner layer and having a sufficient thickness to present a substantial barrier for preventing leakage of volatile hydrocarbons, and (c) a durable outer layer of an elastomer polymer bonded to the outer surface of the intermediate layer and being coextensive with the outer surface of the intermediate layer.
Since the fuel filler hose disclosed in the above-described patent document is aimed to be used for transporting volatile hydrocarbons, it satisfies the permeation resistance to the hydrocarbon vapor as far as gasoline being mixed with no alcohol is concerned. However, its permeation resistance is insufficient to alcohol-blended gasoline (gasohol) fuel containing alcohol having high permeability, such as ethanol.